HoC definitely!
When I was younger I had very dark hair, without a hint of red, and used to wear bright jewel Winter colours (remember back in the day when there were only four seasons!). But as I've got older and faded they've seemed too strong for me. Plus hairdressers and opticians would look at my hazel eyes (lovely amber and turquoise seen close up in bright light, sadly murky dingy hazel when more than a few inches away) and say I was warm.
So, determined to be a Winter, off I went to a CMB consultant who diagnosed me Deep Warm Soft. Meaning I can wear 30 deep colours across the board including black (hurrah!), plus 6 each of deep warm and warm soft, but hardly any light colours and should stick to gold jewelery. (But if I when I let my hair go grey - which would be a lovely steely pewter grey - I would then become cool, whereas HoC say you don't change season, though can change within it.)
This just didn't feel right so off I went to HoC - this time to a training session so it would be free and so that I'd get the expert advice of a trainer. She said I was very difficult to do, started with warm (boo) then cool (hurrah) then back to warm (boo) finally settling on: Blue Autumn on the cusp of Summer!
And it feels exactly right. Apparently I'm very rare which makes me feel quite exotic. Although I'm Autumn I''m right at the far blue (as opposed to yellow) end so my best colours are lovely soft pale or mid tone vintagey colours, or deep rich colours, not the oranges, yellows, khakis and browns you'd typically associate with Autumn. My hair will look lovely if I go grey - whereas a Yellow Autumn would look too dingy - and I can wear silver or gold jewelry but the best thing for me is to wear both together.
I can't believe how quickly and easily I've embraced my inner (Blue) Autumn and have started wearing more beautiful tops rather than boring old white t-shirts. I know people say just say wear whatever colour you want, and of course I still wear things that aren't 'my' colour, but the best thing is that all my new colours really do blend in with each other, and I now wear some colours that I love but would never have worn before.
And although HoC say don't wear black I do cheat a bit and still wear it because CMB says I can. Best of both worlds!
So yes, HoC every time. Although in an ideal world I'd say do both but preferably at a training session.
Good luck!